Allele-specific silencing of the mutant huntingtin gene in a mouse model of Huntington disease

Huntington disease is a fatal and inherited neurodegenerative disease. It is characterized by diminished voluntary motor control, cognitive decline and psychiatric disturbance. Symptoms of the disease first appear in the thirties to fifites, with death usually occurring 15 to 20 years later. While there are still no effective therapies for this disease, recent research discoveries have provided insight into how the disease develops. The normal huntingtin gene encodes a protein that is important for neuronal health. Although everyone has two copies of the huntingtin gene, people with Huntington disease have one normal copy and one mutated copy. When a person has a mutated version the gene, the huntingtin protein accumulates within cells and engages in a variety of aberrant interactions that cause disease symptoms.

Dr. Amber Southwell is working to develop a strategy for turning off the mutant copy of a patient's huntingtin gene in order to prevent or delay the onset of the disease. Her lab has identified genetic characteristics that are more common in mutant than in normal huntingtin genes and have generated therapeutic reagents that specifically target these mutant variations. This effectively switches off the mutant but not the normal gene in cellular models of Huntington disease and results in the selective reduction of the mutant huntingtin protein.

Dr. Southwell will test the efficacy of these candidate therapeutics by measuring their ability to reduce the level of the mutant but not the normal protein in the living brains of a mouse model of Huntington disease. She will also evaluate how the therapeutic reagents influence the behavior and brain pathology of these mice. This targeted approach of selectively silencing the mutant gene while sparing the normal gene is preferable to other approaches that prevent the expression of any huntingtin protein. The normal huntingtin protein is important for neuronal health, and long-term reduction of this protein may not be well tolerated. Hopefully this targeted approach will lead to new therapies to prevent or delay Huntington disease onset.

Mechanisms underlying protective effects of HDL and ABCA1 in beta cell survival

Diabetes is a major cause of disease and death in BC. According to a report from the Canadian Diabetes Association, 7 percent of BC residents currently have a diagnosis of diabetes, and this number is expected to rise to more than 10 percent by 2020, by which time diabetes-associated heath care costs in BC are expected to rise to $1.9 billion per year. Diabetes and cardiovascular disease are intimately related, and having one of these diseases is a strong risk factor for the other. Altered blood cholesterol levels increase the risk of developing both cardiovascular disease and diabetes. Blood cholesterol is carried in two types of particles: low density lipoprotein (LDL) particles and high density lipoprotein (HDL) particles. The HDL is known as the “”good”” cholesterol, as it removes excess cholesterol from tissues and is therefore considered to be protective in the development of cardiovascular disease and diabetes, and people with low levels of the good HDL cholesterol have an increased risk to develop these diseases. Dr. Willeke de Haan is working to understand how these diseases are related at the molecular level. She is specifically examining the interaction between HDL and two cholesterol transporters, ABCA1 and ABCG1. Previous studies have shown that ABCA1 and ABCG1 are both involved in insulin secretion in cells of the pancreas; this provides insight into how HDL cholesterol influences and may contribute to diabetic metabolism. Her research involves both cultured beta cells, a type of cell that secretes insulin from the pancreas, as well as various mouse models of diabetes. Using these models, Dr. de Haan will determine how altering HDL cholesterol levels contributes to diabetes development by analyzing inflammation, stress, death and markers for underlying mechanisms. Her work will also provide essential insights about the function of HDL, ABCA1 and ABCG1 in the development of diabetes and cardiovascular disease, and will validate these molecules as potential targets in the development of novel therapeutic approaches to these diseases.

Development of Clinical Standards of Care for Huntington disease Intermediate Allele Predictive Test Results

Predictive testing for Huntington disease (HD) has been available since 1986. This genetic test has the ability to ‘predict’ whether individuals will develop HD in their lifetime and possibly pass the disease onto their children. Some individuals who undergo predictive testing receive an unusual test result, called an ‘intermediate allele’ (IA), which differs from a gene positive or negative result. While individuals with an IA will never develop HD themselves, there remains a risk that their children or grandchildren could subsequently develop the disorder. Currently, knowledge gaps exist with respect to IA for HD. Specifically, the current International Predictive Testing Guidelines do not address the possibility of this result, nor are the complexities surrounding this result acknowledged in the literature. Alicia Semaka’s research, which is the largest empirical study on HD IAs to date, will not only address these gaps, but also inform the development of clinical standards of care for communicating IA results during predictive testing. The specific objectives of Ms. Semaka’s research are to determine the prevalence of IAs in British Columbia’s general population; determine quantified risk estimates for the likelihood that an individual with an IA will have a child who will develop the disease in their lifetime; and lastly, describe the psychological and social impact of receiving an IA result. Collectively, the three objectives of this unique, multidisciplinary study will provide the foundation for the development of clinical standards and practice recommendations for IA predictive test results. These standards will help ensure that this subset of patients receive appropriate information, support, education and counselling throughout the predictive testing process.

Role of beta-cell Toll-like receptor signalling in type 2 diabetes

Diabetes mellitus is a chronic disease that affects over 180 million people worldwide. At least two million Canadians currently live with the condition, a figure expected to double in the next 10 years. Type 2 diabetes accounts for 90 percent of cases and has been recognized by the World Health Organization as a global epidemic. Thus, urgent action is needed to reduce the economic and social burden of the disease and its complications. Diabetes is characterized by insufficient production of insulin, a hormone released by the pancreas that regulates blood glucose levels. Type 1 diabetes is an autoimmune disease caused by destruction of insulin-producing beta-cells within the pancreatic islets. Type 2 diabetes is characterized both by resistance to insulin action and by impaired beta-cell insulin production. Inflammation, an immune response to tissue damage, is important in both conditions. Islets from patients with Type 2 diabetes exhibit increased levels of pro-inflammatory cells and proteins. These contribute to beta-cell damage and impaired insulin production, representing a potential target for therapeutic intervention. High circulating levels of glucose and fatty acids, in addition to toxic deposits of a small protein called islet amyloid polypeptide (IAPP), may signal via pattern recognition receptors on cells within the islet to promote an inflammatory state. However, a better understanding of the causes of islet inflammation is required for effective development of targeted therapies. Clara Westwell-Roper’s research focuses on the role of pattern recognition receptor signalling in islet inflammation induced by metabolic stimuli and IAPP. Her research will enhance our knowledge of the mechanisms that contribute to beta-cell death and impaired insulin secretion in patients with Type 2 diabetes. An understanding of the causes of islet inflammation may facilitate the development of new medications that improve pancreatic islet function.

The Role of Palmitoylation in the Pathogenesis of Huntington Disease

Huntington disease (HD), is an adult-onset progressive, degenerative disease affecting the neurons of a particular area of the brain called the striatum. The striatum is partially responsible for regulating movement, and HD affects the part of the striatum responsible for inhibiting unwanted movement. The primary symptom of HD is chorea, or involuntary “”dance-like”” movements. Currently, no effective treatment or cures exist, and death occurs on average 15 years after disease onset. HD is caused by a mutation in the Huntington gene where a short sequence at the beginning of the gene is multiplied, resulting in more than 36 repetitions. The mutation is inherited, so that people with HD have a 50 percent chance of passing it onto their children. The mutation has many effects on the function of the Huntington protein (htt), including interfering with how it interacts with other proteins, such as Huntington Interacting Protein 14 (HIP14). HIP14 is a “”PAT”” enzyme, which is a type of enzyme involved in a process called palmitoylation. There is a growing body of evidence to suggest that palmitoylation plays an important role in HD. Shaun Sanders’ research into HD involves the development of a new, genetically modified “conditional knockout” mouse model. Using this model, Sanders can “”turn off”” HIP14 when and where wanted, in a particular organ or area of an organ, like turning a light off in one room but not in another. He will then look for the symptoms of HD in the mouse model. His research will provide more evidence for the role of HIP14 in HD and further validate the model of palmitoylation in HD. The results will also improve our knowledge regarding “”PAT”” enzymes and palmitoylation which will expand the understanding of other neurological diseases, such as Schizophrenia and mental retardation.

Population trend in fertility drug use and its impact on birth outcomes.

The trend towards delayed childbearing has accelerated in recent decades, and as a result more women find it difficult to become pregnant. Consequently, the use of fertility drugs and assisted reproductive techniques, such as in-vitro-fertilization, has increased. The most profound population effect of these fertility treatments is an increase in multiple births (twins, triplets and higher order multiples), and recent data from Statistics Canada show a continued increase in these types of births. Unfortunately, this unintended increase in multiple births carries a considerably higher risk of pregnancy complications and adverse outcomes in newborns, and therefore carries implications for public health. While evidence suggests that use of fertility drugs is the most significant contributor to multiple pregnancies, identifying the proportion of births that result from the use of fertility drugs alone remains challenging. Further, there is little current information in Canada regarding the temporal trend in fertility drug use and the number of women who currently use these treatments. And, little is known about the impact of fertility drugs alone (without any invasive procedure). Dr. Sarka Lisonkova’s research will provide much needed information on pregnancy and perinatal outcomes including multiple pregnancies, congenital anomalies, miscarriages and pregnancy terminations, stillbirths, preterm births and neonatal deaths among women who did and did not use fertility drugs. By utilizing systematically collected population-based pharmaceutical and health related data available in BC she can identify the trend in fertility drug use among BC women between 1996 and 2006, as well as the maternal age distribution and demographic characteristics of those women. This information is important and timely, and the results will not only inform the women who have difficulty becoming pregnant about potential risks associated with fertility drugs, but also provide useful information to health services planners and administrators.

Targeting the Ras/MAPK pathway for treatment of high-grade pediatric brain tumors

Brain cancer is an extremely aggressive disease that remains difficult to cure and carries a high mortality rate. Every year, more than 3,500 children in North America are diagnosed with this disease. Brain tumours are the most common solid tumours and the second leading cause (after leukemia), of cancer-related deaths in children. The majority of patients (80 percent), with the more aggressive forms of brain tumours will survive less than two years. Surgical removal of brain tumours is challenging for a number of reasons, and complete removal of cancer cells is virtually impossible. The chemotherapeutic agent Temozolomide (TMZ), is used in patients with aggressive brain cancers however, in a subgroup of patients this drug does not work effectively because they are resistant to it. Furthermore, recent research shows that TMZ is not generally very effective at eliminating pediatric brain tumour cells. Consequently, certain ‘survivor’ tumour cells become ‘seeds’, generating more cells that subsequently form a new tumour. Cathy Lee’s research focuses on a protein called PLK1, which is essential to the cell division process in cancer cells. Many researchers have shown that PLK1 levels are higher in cancer cells than in normal cells and that tumour cells require this protein for survival. When this protein is eliminated, cancer cells either die or their growth is suppressed. Importantly, normal cells do not seem to be greatly affected by PLK1. Ms. Lee’s research will provide a deeper understanding of this protein. In related research, Lee will examine the ‘seeds’ of brain tumours, called ‘brain tumour initiating cells’, with a view to determining a way to prevent their expansion and induce cell death. The results of her research will improve our understanding of pediatric brain cancers and allow future design of novel, alternative therapeutic strategies that benefit patients’ health and improve the way we currently treat this devastating disease.

Defining Immune Abnormalities And Their Consequences In The HIV Exposed But Uninfected Child

The primary route of infection for human immunodeficiency virus (HIV), in infants is from mother to child. Following the introduction of ‘Prevention of Mother To Child Transmission’ (PMTCT), programs, HIV infection rates in newborns from mother to child (vertical transmission), have been reduced from 30 percent to less than five percent. As a result, the number of ‘HIV Exposed but Uninfected’ infants (HEU) has steadily risen. In South Africa, where 30 percent of all women of childbearing age are HIV infected, 300,000 HEU births occur per year. Recently, infection and death rates among HEU infants have been determined to be much higher than those in HIV unexposed (UE) infants. Consequently, there is an urgent need to understand why HEU infants are so vulnerable to infections. Briefly, when a person is exposed to an infecting microbe, two major arms of the immune system respond: innate immunity, which keeps the microbe at bay, and adaptive immunity, which eventually clears the infection. While it is now known that alterations in the adaptive immune system of HEU infants do take place, there is little known about how the innate immune system of HEU compared to that of the UE infant. Mr. Brian Reikie, working in collaboration with Stellenbosch University, South Africa, is conducting a pilot study to determine whether exposure to HIV, in the womb or around birth, activates the innate immune system, which then causes damage to the adaptive immune system. As well, he will explore the HIV-innate-adaptive interaction to help explain why HEU infants are so susceptible to infections. Beyond the study of HEU, this will be the first demonstration of how innate immune responsiveness correlates with development of either normal or altered adaptive vaccine immune responses over time. The findings from this project will provide the essential groundwork for urgently needed guidelines for appropriate treatment and clinical follow-up of this vulnerable population.

Vascular dysfunction of the arteries in a mouse model of Marfan syndrome

Marfan syndrome is an inherited disorder of the connective tissue that causes abnormalities of the eyes, cardiovascular system, and musculoskeletal system. Its most serious and deadly complication is ballooning and rupture of the aorta, the major blood vessel that carries blood from the heart to the arteries and organs. The syndrome is caused by a defect in the gene that makes fibrillin-1 protein. Fibrillin-1 is essential in the formation of elastic fibres in arteries and in maintaining the functional and structural integrity of blood vessels’ endothelial and smooth muscle cells. Defects in this gene result in abnormalities in the way vessels contract and relax, increasing the susceptibility to ballooning and rupture of the aorta. Huei-Hsin Clarice Yang is studying the effect of Marfan syndrome on endothelial and smooth muscle cells in the aorta and the small arteries. She is expanding on previous research that found that smooth muscle in the Marfan-affected aortas is unable to relax normally. Her work focuses on the mechanisms that contribute to this dysfunction within smooth muscle cells and in the epilethial cells that regulate vascular contraction and relaxation. Yang’s work will provide valuable insight into how Marfan syndrome causes decreased contracting and relaxing abilities of the arteries. Ultimately, this knowledge could lead to innovative therapies to prevent or treat aortic rupture and to halt the vascular deterioration process in patients with Marfan syndrome